Permanent magnets based on the RE.sub.2 Fe.sub.14 B-type structure have gained wide commercial acceptance. Such magnets can be made by a sintering practice, and they can be made by rapidly solidifying a melt of suitable composition and producing bonded magnets or hot pressed magnets or hot pressed and hot worked magnets from the quenched material.
Recently, rare earth-iron-carbon compositions have been formed in the RE.sub.2 Fe.sub.14 C structure which is analogous to the above-mentioned iron-rare earth-boron structure. Stadelmaier and Liu, U.S. Pat. No. 4,849,035, cast iron-dysprosium-carbon compositions and iron-dysprosiumneodymium-carbon-boron compositions in the form of ingots and through a prolonged annealing cycle at 900.degree. C. produced the magnetically hard tetragonal 2-14-1 structure. The casting displayed permanent magnet properties as did comminuted particles produced from the casting. The comminuted particles were disclosed as suitable for use in a bonded magnet. While such materials displayed appreciable coercivity, they displayed relatively low remanence.
Coehoorn et al., "Permanent Magnetic Materials Based on Nd.sub.2 Fe.sub.14 C Prepared by Melt Spinning", Journal of Applied Physics, Vol. 62, No. 2, 15 January 1989, pp. 704-709, produced melt-spun ribbon particles of neodymium, iron and carbon which, when annealed at a suitable temperature, produced a permanent magnet of the 2-14-1 structure. Such particles could also be used to make a resin-bonded magnet.
It is an object of our invention to provide hot worked magnets, e.g., hot pressed or hot pressed and die upset magnets, of the Nd.sub.2 Fe.sub.14 C-type structure that have very fine grains, have permanent magnet characteristics and are magnetically anisotropic. It is another object of our invention to provide a method of making such hot worked magnets.